유용스크립트들 isObject, isString, isUndefined...

<script>
function isIEObject(a){
    return isObject(a) && typeof a.constructor != 'function';
} 
function isArray(a){
    return isObject(a) && a.constructor == Array;
}
function isBoolean(a) {
    return typeof a == 'boolean';
}
function isEmpty(o){
    if (isObject(o)){
        for (var i in o){
            return false;
        }
    }
    return true;
}
function isFunction(a){
    return typeof a == 'function';
}
function isNull(a){
    return typeof a == 'object' && !a;
}
function isNumber(a){
    return typeof a == 'number' && isFinite(a);
}
function isObject(a){
    return (typeof a == 'object' && !!a) || isFunction(a);
}
function isString(a){
    return typeof a == 'string';
}
function isUndefined(a){
    return typeof a == 'undefined';
}
</script>